The PRIME Study was begun in 1991 and recruited 10,600 men aged 50 to 59 years in the WHO MONICA Project centers of Belfast, Lille, Strasbourg and Toulouse. Although drinkers in France and Northern Ireland consumed almost identical amounts, the pattern of consumption was different. In Northern Ireland beer and spirits were the staple beverages, whereas in France it was predominantly red wine; in France, 90% of men drank at least one unit per week versus 61% in Northern Ireland. Frenchmen drank evenly throughout the week, whereas in Northern Ireland two thirds of the consumption took place on Friday and Saturday nights.

In the 5-year follow up of PRIME in France, the usual cardiovascular protective effect of increasing consumption (up to 45 units per week) was shown and the level of significance for trend in consumption was highly significant (p = 0.006); in Northern Ireland, this pattern was less consistent and did not attain significance. It remains a matter of conjecture whether in Northern Ireland the beneficial effects of alcohol consumption were annulled by a pattern of drinking that increases blood pressure, a well-established risk factor for heart disease, or whether the protection in France resulted from the consumption of wine along with food.